Teshuvah [repentance] occupies the greatest portion of Torah and Life, and upon it are founded all of the hopes of the individual and the community.

From Perek 5:

העולם מוכרח הוא לבא לידי תשובה שלימה

The universe is compelled to come to complete teshuvah.

And, most powerfully, from Perek 6:

אין דבר בטוח בעולם כמו התשובה

Nothing in this universe is as certain as teshuvah.

I cry when I read this sentences. Okay, I cry easily, but still - I haven't been this moved by a Torah text since the first time I read Rav Shimshon Raphael Hirsch.

Rav Kook spends a lot of time on the mystical character of teshuvah - how it ties into the fundamental nature of the universe, why it is necessary, how it influences one's actions in the past as well as the future - but he doesn't use mystical jargon. I find it inspiring, very readable, and very worthwhile.

Just so you know, you inspired me to start teaching Orot HaTeshuva in my shul between mincha/maariv on Friday night and during seudah shlishit. I have always skimmed parts of it but never fully delved into it. If one takes the time to really sit with it, there are tremendous insights.